After her cat goes missing during a blizzard, cartoonist Penny is thrown into a spiral of grief. When her boyfriend invites her to a party hosted by an investment client, Penny spends the party with their cat, Godfrey.
When she is offered the chance to petsit Godfrey for a month, Penny wonders if this could be just what she needs. But as soon as she takes Godfrey into her home, things begin to change. A series of strange, unexplainable occurrences gradually leads Penny to believe that Godfrey isn't a cat after all - but an ancient demon hell-bent on hijacking her mind, body and spirit...
